The invention relates to a device for the implantation of microcoils into body cavities and blood vessels, in particular aneurysms, with the microcoils comprising wires forming a plurality of windings, at least one microcoil serving as occlusion helix for the occlusion of the body cavity or blood vessel, and the device consisting of a catheter, one or several microcoils movably arranged in longitudinal direction within the catheter and at least one securing means passing at least partially through the lumen of the occlusion helix, with the securing means being fixed in its end areas inside the microcoils. Furthermore, the invention relates to an occlusion helix to be used in connection with the aforedescribed device.
The use of endovascular techniques for the occlusion of body cavities or vessels such as arteries, veins, fallopian tubes or vascular deformities (for example, vascular aneurysms) is known in the art. In this case, the occlusion helix is usually introduced by means of an endovascular insertion wire through a catheter into the cavity to be occluded and deposited therein.
Before placement may commence the occlusion helixes are maneuvered with the help of the catheter through the blood vessel system and, at the target site, advanced out of the catheter and into the cavity to be occluded. Ideally, the separation/severance of the helix follows these steps. In the event of a wrong placement of the occlusion helix or if too large an occlusion helix has been selected for the area to be occluded the helix must then be repositioned or completely retracted into the catheter to subsequently enable such an occlusion helix to be correctly positioned or a correctly sized helix to be placed in position. Maneuvers of this kind involve risks in that parts of the helix are pulled apart and elongated due to the tensile or torsional stresses applied, and in this way become plastically deformed irreversibly, are torn off or broken which may give rise to life-threatening embolism.
To minimize this danger it has been known, inter alia from the European Patent Specification EP 0 792 623 B1, to provide for a polymeric, non-extensible element passing through the lumen of the occlusion helix, the element being permanently attached to the occlusion helix at two places at least. Such a design enables an occlusion helix to be repositioned or retracted into the catheter in such a manner that it is not pulled apart and elongated so that an irreversible deformation can be avoided.
However, this prior-art technique has the disadvantage in that the polymer thread may suddenly break in the event that too high a retraction force is exerted. In such a case the entire tensile load suddenly acts on the occlusion helix itself which may cause not only deformation but may even lead to occlusion helix breakage. Since such a break of the polymer thread may occur all of a sudden the detrimental effects caused in the blood vessel may be considerable and can hardly be controlled.
In view of the problems described above it is therefore the object of the invention to provide a device for the implantation of occlusion helixes that permit a higher degree of safety to be achieved for patients when occlusion helixes are inserted and placed than can be brought about by prior-art means.